DC brushless motor adopts electric commutating device instead of the traditional mechanical commutating device (commutator and carbon brush),it not only keep the good speed regulation and starting features of DC motor, but also has advantage of AC motor, such as simple structure and easy maintainence etc.

DC brushless motor has good and stable performance, so it developped quickly in recent years. The armature of traditional DC motor is rotatory,and magnetic pole is static, but DC brushless motor is on the contrary, magnetic pole is rotatory, armature is static, the commutating of armature winding can be achieved by position sensor and electric switch circuit.

Usually,DC brushless motor consists of motor,position sensor and electric switch. Electric motor consists of multi-phase(three phase,four phase,five phase ect.) armature winding and stator and permanent magnetic rotor with a certaina certain number of pole-pairs. AA,BB,CC stand for three phase stator winding, NS is permanent magnetic pole,it is motor's armature, PS is the armature position sensor which connects on the same shaft of motor aramture, BG1,BG2,BG3 is the power switch tube of electric switch circuit, three phase winding A.B.C are serial connected with BG1,BG2,BG3 respectively, then connect to the power source. Its action principle is: PS give a signal to control BG1,BG2,BG3 on and off,when power switch tube is on, there will be current go through the corresponding stator winding, and generate magnetic field, the magnetic field interact with magnetic pole of permanent rotor and generate torque to make motor armature rotate, as the position sensor is connected on the same shaft of motor, so its armature will rotate at same time and give signal to BG1,BG2,BG3 orderly to control the power switch tube on and off, so as to make the current in armaturecommutating orderly along with the armature position changing, and make the armature magnetic field rotate in stepping mode,thus motor armature will keep rotating continously.